The prevailing design methodology of mobile computing devices (such as smart phones, tablets devices, netbooks, personal data assistants, portable media devices, wearable devices, etc.) emphasizes slimmer profiles while offering ever increasing processing and image rendering capabilities and larger display sizes. As a natural result of minimizing the width or thickness of the underlying mobile computing devices, a similar trend of minimizing the height of the internal modules has developed out of necessity.
A common implementation of a mobile computing device includes a main printed circuit board (PCB) having one or more processing elements. The distinct lack of internal space due to the smaller form factor not only makes heat dissipation more critical, but also presents additional challenges for heat distribution and dispersal. Moreover, other components (such as camera modules, battery modules, etc.) also generate heat during operation. A popular solution for managing heat levels in mobile computing devices is through the use of performance throttling.
Performance throttling is performed by intentionally limiting or reducing performance levels of components in a system below the highest possible level(s) in order to reduce a heat generated during operation/usage. Typically, a component such as a processor is able to operate at the highest possible rates (e.g., processing frequencies) for a relatively short period. When the heat (as determined by sensors) generated by the processor due to operation exceeds a threshold, operating rates are throttled to reduce the heat produced commensurately. Typically, the threshold at which the performance is throttled corresponds to a higher level of risk with respect to user comfort, or to comply with safe operating limits with respect to the component. However, throttling the performance can negatively impact user experience, since performance levels are reduced, sometimes perceptibly.
To address the throttling issue, recently proposed solutions have incorporated materials with phase changing properties for thermal management. Proposed implementations include heat sink fins interspersed with portions of phase change material, compositions that mix phase change materials with other materials for structural effect, and adhering phase change materials on system-on-chips. However, the proposed solutions each present different issues that may be less than ideal. For example, heat sink fins interspersed with phase change materials would be limited to phase change materials with significantly high melting points, as liquids would not be bound by such a structure, and may leak or otherwise escape from between the heat sink fins. Meanwhile, phase change materials mixed with materials for structural effect (typically graphite or other such compositions) are often mixed with materials that do not exhibit the same thermal properties. Typically, the materials have less ideal thermal properties, such as less heat absorption efficiency. As such, the efficacy of these solutions can be significantly less than solutions where the phase change material is unadulterated. Likewise, adhering phase change materials on system-on-chips would require additional steps, such as encapsulating the phase change materials in molding compounds, that would increase the height of such structures.